This invention relates generally to sequencing valves for sequentially selectively coupling one of a plurality of outlet conduits with a single supply conduit that sequentially actuate in response to a change in supply fluid pressure, and more particularly to an indicating means for providing visual indication of which particular outlet conduit is connected to the supply conduit at any particular time.
Valves of this general type that provide no visible indication are described by the following U.S. Patents: U.S. Pat. No. 4,125,124 issued 11/78 to Kah; U.S. Pat. No. 4,083,290 issued 4/78 to Andres; U.S. Pat. No. 4,178,963 issued 12/79 to Riefler; U.S. Pat. No. 4,195,665 issued 4/80 to Nolan and U.S. Pat. No. 3,924,652 issued 12/75 to Kah. U.S. Pat. No. 4,796,657 issued 1/89 to Baker, the applicant, teaches a manual selecting and locking control for these valves, but also without external means for indicating which outlet has been selected.
U.S. Pat. No. 4,492,247 issued 1/85 to Lockwood does teach a sequencing valve with an external indicator in the form of a rotatable external disc 16 mechanically coupled to the internal rotary shaft of the valve. Because a valve of this type is exposed to all manner of dirt and debris, the disc may be prevented from turning by trapped foreign matter. Since the disc is mechanically coupled to the operating shaft of the valve, this will in turn prevent the valve from operating. Transparent covers for the valve that would simply allow view of the inner shaft position are not feasible because the inner surface of the cover is promptly obscured by impurities in the irrigation water.